Carbon footprint

A measure of how much heat a greenhouse gas traps in the atmosphere over a set time period relative to carbon dioxide, allowing emissions of different gases to be expressed as a single carbon dioxide equivalent figure. GWP is the headline indicator in most environmental product declarations and carbon footprint studies.

A standardised method, set out in ISO 14040 and ISO 14044, for quantifying the environmental impacts of a product or system across its life, from raw material extraction through manufacture and use to end-of-life. LCA results underpin environmental product declarations and embodied carbon calculations used in material selection.

The greenhouse gas emissions associated with producing a material or product, covering raw material extraction, processing, manufacture and transport, and in whole-building assessments also construction, maintenance and end-of-life stages. It is expressed as carbon dioxide equivalent and is commonly reported through environmental product declarations.

A life cycle assessment boundary covering raw material extraction through to the point where the product leaves the factory gate, excluding transport to site, installation, use and end-of-life. In construction EPDs to EN 15804 this corresponds to the product stage, modules A1 to A3.